1. Field of the Invention
The invention relates to the field of photography and, more particularly, to a photographic apparatus including a switching device which may be actuated manually and automatically to initiate a cycle whereby a foremost member of a film laden cassette intimately including an opaque light shield is removed.
2. Description of the Prior Art
Cameras intended for use by amateur photographers are designed with a viewpoint of reducing requisite preparatory adjustments for obtaining a quality finished print of a desired scene. Numerous automatic features have been introduced to minimize both post-exposure and pre-exposure camera preparations thereby requiring only nominal operator participation. Cameras incorporating self-processing features have been devised wherein previous manually operated roller systems for processing film units having a processing liquid between elements of the film units have been replaced by motorized roller systems which automatically process the film units following an exposure thereof. Film loading has been simplified with the introduction of disposable film cassettes designed for positioning photosensitive surfaces of the film unit at an exposure plane of the camera merely by direct insertion of the cassette into a receiving chamber included within the camera. Such a cassette is described and claimed in detail in U.S. Pat. Nos. 3,543,662; 3,651,746; and 3,705,542 wherein a selected number of photosensitive film units preferably of the self-developing type and intimately including therein an opaque light shield or dark slide cover in superposition to the film units are arranged in stacked relation and adapted to be sequentially presented at the exposure plane of the camera. The cassette is adapted for use with an automatic camera which operates to expose, process and transport individual film units each of which is formed incorporating a pod of processing fluid which is spread within each film unit to initiate formation of a visible positive image.
The cassette includes a housing formed to provide a film frame opening which when positioned within a receiving chamber of the camera sequentially positions each foremost member of an assemblage of the film units and the dark slide at the exposure plane of the camera. The assemblage is arranged in stacked relationship with the dark slide cover as a foremost member of the assemblage. Prior to insertion of the cassette into the receiving chamber, the dark slide cover is positioned over a film frame opening to secure light from the opening and protect the photosensitive surfaces of the film units. The dark slide is subsequently removed after the cassette has been properly positioned within the receiving chamber of the camera.
Improved versions of cameras adapted for use with the cassette have employed a variety of switching devices and complex electrical control circuits which automatically remove the dark slide from within the cassette when the cassette is inserted into the receiving chamber and the receiving chamber rendered lighttight. A typical example of a photographic apparatus including such a control system is described in detail in U.S. Pat. No. 3,750,551 issued to Edwin H. Land and Peter P. Garcia, on Aug. 7, 1973, wherein automatic removal of a dark slide cover is carried out upon the closing of designated switches within the system to initiate a dark slide ejection cycle which substantially overrides a normal operational photographic exposure cycle of the camera. One of the switching members, closed to activate the dark slide ejection cycle, is employed only during the dark slide ejection cycle and is subsequently disengaged upon the completion of the cycle and remains disengaged throughout each normal operational exposure cycle. When the cassette is emptied, removed from within the receiving chamber, and replaced by a fresh cassette, the switching member is again employed but once again only during the dark slide ejection cycle. Therefore, subsequent to the dark slide ejection cycle, exposed film units are removed from their underlying position within the cassette and processed by actuating a second switching member which activates a normal operational cycle of the camera having an exposure cycle and a processing cycle wherein the exposed film unit is ejected from the camera. A control system of this type includes a switching member which is employed only once during any of the operational cycles of the camera and further requires additional switching members and may include an electrical control circuit design requiring additional components to prevent the normal operational photographic exposure cycle from operating during the dark slide ejection cycle. Such a control system may be considered unduly complex and lacking in efficient use of components thereby resulting in an expense which is not warranted to provide substantially similar preexposure and post-exposure operations. In accordance with the present invention, it will be seen that a substantially similar simplified operation is completed satisfying all the necessary requirements, i.e., performing substantially similar functions as described in the prior art by utilizing a switching feature, which is highly reliable and incorporates substantially fewer parts.